The long-term objective of this project is to characterize homologous genetic recombination in plants. This work will focus primarily on the small crucifer Arabidopsis thaliana as a model system, and secondarily on the related brassica cauliflower (Brassica oleracea var. botrytis. Specific aims are: (1) to complete purification of recominase activity and characterize the enzyme(s); (2) to clone and sequence the corresponding gene(s) and flanking regulatory regions; (3) to construct Arabidopsis lines carrying markers suitable for scoring various crossover events, and begin characterizing those events in various conditions. Future likely directions include determination of recombinase genetic regulatory mechanisms, of the effects of altered recombinase gene expression, and of the role of mitotic and meiotic recombination in the plant life cycle. This work, besides providing information about a fundamental biological process, could eventually allow that process to be manipulated experimentally as well. In the long term that could be of value in the genetic engineering of agronomically important crops, to the benefit of human nutrition and health.